Membrane switch with first and second independently movable portions



Feb. 7, 1967 M FISCHER ETAL 3,303,306

MEMBRANE SWITCH WITH FIRST AND SECOND INDEPENDENTLY MOVABLE PORTIONSFiled July 27, 1964 INVENTORS "l a. T72 J1 11L 6 I United States Patent3 303 306 MEMBRANE SWETCH WITH FIRST AND SECOND INDEPENDENTLY MOVAELEPORTEGNS Max Fischer, Goppiugen, and Gerhard Brink, Zutfenhausen,Germany, assignors to Robert Bosch G.rn.h.H., Stuttgart, Germany FiledJuly 27, 1964, Ser. No. 385,186 Claims priority, application Germany,Juiy 25, 1963, B 72,838 18 Claims. (Cl. zen-s3 The present inventionrelates to a membrane switch, and more particularly to a membrane switchresponsive to different pressures of a controlling fluid to operatedifferent contact means.

Electrical membrane switches are known, and in accordance with prior artconstructions, the displacement of a membrane by the pressure of thefluid is transmitted by linkage means to two or more contact means foractuating the same. The constructions of the prior art are complicated,include very delicate parts, and are expensive to manufacture,particularly since the assembly and mounting of the many parts in thehousing of the pressure responsive switch causes great difficulties andis time consuming.

It is one object of the present invention to overcome the disadvantagesof membrane switches according to the prior art, and to provide amembrane switch of simple construction in which a plurality ofelectrical contact means are operated by the varying pressure of acontrolling fluid acting on the membrane.

Another object of the invention is to provide a membrane switch withindependently movable membrane portions which individually controlcorrelated contact means.

Another object of the invention is to provide a membrane switch in whicheach individually movable membrane portion is directly connected byrigid actuating means to a correlated electrical contact means, so thatthe linkages of the prior art are avoided.

Another object of the invention is to provide a membrane switch with amembrane having a plurality of individually movable membrane portionswhich are biased to respond to different actuating pressures of acontrolling fluid acting on the membrane so that contact means aresuccessively actuated.

Another object of the invention is to differently bias the electricalcontact means of a membrane switch, and to connect each contact means toan independently movable portion or" a membrane so that different fluidpressures cause selective actuation of the contact means.

With these objects in view, the present invention relates to a membraneswitch which comprises a membrane mounted on a support and including aplurality of independently movable membrane portions which are,respectively, connected to a plurality of contact means for actuatingthe same when the respective membrane portion is displaced. A pluralityof biasing means is provided for applying different forces to one sideof the membrane portions, preferably through actuating means connectinga contact means with the membrane portions, so that fluid pressureapplied to the membrane portions will cause actuation of the contactmeans whose correlated membrane portions are displaced at differentpressures by the pres sure fluid.

One embodiment of the invention comprises a support, such as a housingwhich is divided by the membrane into a chamber for the fluid, andanother chamber in which the contact means are mounted. Each contactmeans includes an actuating member on which a biasing means, preferablyin the form of an adjustable spring acts. The actuating member isconnected by actuating means to a corresponding membrane portion of themembrane,

3,303,306 Patented Feb. 7, 1967 and such actuating means include rigidmembers secured to the respective membrane portion.

In one embodiment of the invention, two membrane portions are separatedby a fold in the membrane to be individually displaceable by the fluidpressure, and a segment-shaped plate is secured to each membraneportion. In another embodiment of the invention, a circular fold in themembrane separates a circular membrane portion from an outer annularmembrane portion, and one actuating means which is connected to onecontact means includes a plate secured to the inner portion, while theother actuating means cooperating with the other contact means, includesa bell-shaped member whose rim is secured to the annular membraneportion.

In all embodiments of the invention the actuating members of the severalcontact means are directly connected to individually movable membraneportions, so that no linkages are required.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. 1 is a longitudinal axial section illustrating one embodiment ofthe invention;

FIG. 2 is a cross sectional view taken on line II-II in FIG. 1; and

FIG. 3 is a side elevation, partly in axial section, illusstratinganother embodiment of the invention.

Referring now to the drawings, and more particularly to FIGS. 1 and 2,the housing of the membrane switch is composed of a generally pot-shapedhousing part 1 consisting of an insulating material, and being closed bya cover means having a crimped edge secured to a flange of housingpart 1. Between cover 2 and housing part 1, the peripheral edge portion3 of a membrane 4 is clamped so that the interior of the housing isdivided into a chamber 7 and into a chamber 8. Chamber 7 has a tubularinlet means 5 secured to cover 2 and provided with a throttle opening 6.Pressure fluid can be supplied through inlet means 5 into chamber 7, andwill act on one side of membrane 4 to displace the same toward chamber8. A straight fold 17 is provided in membrane 4, dividing the same intotwo substantially segment-shaped membrane portions which areindividually movable due to the provision of fold 17. For example, whenone of the segment-shaped membrane portions is prevented from movement,the pressure of the pressure fluid in chamber 7 will still be able todisplace the other membrane portion.

Two contact means, constructed as snap-over switches, are disposed inchamber 8. Each contact means has a frame-shaped arm 9, carrying acontact piece 10, and adapted to move between two positions including acircuit closing position in which contact piece 10 abuts another contactpiece, not shown, on housing part 1. An actuating tongue member 11projects into the cutout of contact arm 9 and is connected by a spring12 to the opposite part of contact arm 9.

Housing part 1 has two projections, in which springs 13 are mountedwhich respectively abut the ends of actuating tongue members 11 to biasthe same to move toward membrane 4-. Adjusting screws 14 are mounted inthreaded parts of the projections on housing part 1, and areindividually adjustable for adjusting the spring tension of biasingsprings 13.

Springs 13 are diiferently adjusted to produce diiferent forces onactuating member 11, and such forces are transmitted to the membraneportions by actuating means 18 and 19 whose upper ends support actuatingmembers 11 at the points at which springs 13 act. Actuating means 18 and19 include plates 15 and 16 which are segmentshaped, as best seen inFIG. 2, and which are respectively secured to the two membrane portionsand separated by fol-d 17 in membrane 4. The straight edges 15 and 16'of the segmentashaped plates 15 and 16 are disposed directly adjacentthe flexible fold 17. As a result, it is possible to move the plates 15and 16 independently of each other together with the correspondingmembrane portions.

While plates 15 and 16 are located in chamber 8 on one side of membrane4, other plates 4a are secured to the other side of membrane 4 andcooperate with inwardly raised beads in cover plate 2 which are engagedby plates 4a when the pressure of .springs 13 urges the membranedownward, as viewed in FIG. 1.

When pressure fluid is admitted through throttle 6 and inlet means inchamber 7, the same pressure acts on the two membrane portions and istransmitted through the actuating means 15, t8 and 16, 19 to theactuating members 11 of the contact means 9. Assuming that spring 13 onthe left side of FIG. 1 is adjusted to produce a lesser force than theother spring 13, increase of. the pressure of the. pressure fluid inchamber 7 will first displace the membrane portion on the left side, asviewed in the drawing, so that the corresponding actuating. member willbe moved upward, and cause the corresponding contact means to assume acircuit closing position. contact means 9 is not yet actuated, since therespective pressure of the pressurefluid is insufficient to overcome thegreater force produced by the differently adjusted spring 13 on theright side of the FIG. 1. However, after the pressure of the pressurefluid in chamber 7 has been increased to be sufficient to overcome theforce of the spring 13 on the right side of FIG. 1, the correspondingcontact means is actuated.

The independent actuation of the contact means by the pressure fiuid ispossible due to the fact that the two portions of membrane 4 which areseparated by fold 17, are independently movable so that displacement ofthe left membrane portion will not cause displacement of the rightmembrane portion which is, at first, held back by the greater force ofthe corresponding spring 13.

While in the above described construction of FIGS. 1 and 2, theincreasing pressure causes actuation of the contact means to close acircuit, it is evident that the construction can be reversed, so thatincreased pressure will cause breaking of a circuit.

The embodiment illustrated in FIG. 3 corresponds substantially to theembodiment described with reference to FIGS. 1 and 2, and correspondingparts are indicated by like reference numerals. Instead of twosegment-shaped movable membrane portions, and two correspondingsegment-shaped plates 15 and 16, the embodiment of FIG. 3 provides aninner central substantially circular membrane portion separated byacircular inwardly convex told 22 from an outer annular membrane portion.

The actuating means for the contact means 9 on the left side of FIG. 3include a circular plate 21 secured to the central portion of the,membrane, and having a perpendicu larly projecting arm 24 connected tothe actuating member 11 of the respective contact means 9. The actuatingmeans for the contact means on the right side of FIG. 3, include abell-shaped member 2t) whose lower rim is secured to the annularmembrane portion outside of fold 22, and whose top has an opening 24through which projecting arm 23 of member 21 passes.

The central portion of the ,top of bell-shaped member 21 has a guideportion 26 with a guide bore through which a guide pin 25 secured to theplate member 21 passes.' The free end of guide pin 25 is lguided in aguide means 27 provided on housing part 1. Bell-shaped member 20 has aprojection 29 on its top connected to actuating member 11 so that thepressure of spring 13 on The other V 4'. the right side of FIG. 3 istransmitted to the bell-shaped member 2% and from there to the outerannular membrane portion. Guide members 25, 2d and 27', which areparallel to projection 29 and projecting arm 23, assure a parallelmovement of members 20 and 21, and the centering of member 20 relativeto member 21. In the embodiment of PEG. 3 a lesser pressure of the fluidin chamber 7 will be sufiicient to displace the annular membrane portionand to shift actuating means 20, 26 so that contact means 9 on the rightside of FIG. 3 is first actuated. When the pressure of the fluid isincreased, it is sufficient to displace the central membrane portionwith member 21 so that contact means 9 on the left side is actuated.

While the disclosed embodiments provide only two contact means andcorresponding movable membrane portions, a greater number of contactmeans and independently movable membrane portions can be provided.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofmembrane switches differing from the types described above.

While the invention has been illustrated and described as embodied in amembrane switch in which two independently movable membrane portionsrespond to different pressures to individually actuate two contactmeans, it is not intended to be limited to the details shown, sincevarious modifications and structural changes may be made withoutdeparting in any Way from the spirit of the present invention. V

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of, this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is: t

1. A membrane switch comprising, in combination, a support; membranemeans mounted on said support and including a first movable membraneportion, a second movable membrane portion, and means intermediate saidfirst and second movable membrane portions and including a poition ofsaid membrane means and permitting said movable membrane portions tomove substantially independently of each other; a plurality of contactmeans mounted on said support, each contact means including an actuatingmember movable between two positions; biasing means on said support forholding said members in one of said positions, said biasing means actingon said actuating members with different forces; a plurality ofactuating means connecting said membrane portions with said actuatingmembers, respectively, so that different forces are transmitted to saidmembrane portions and movement of each membrane portion causes movementof the correlated actuating member to the other position thereof; andmeans for applying a fluid to said membrane portions so that saidactuating'mem bers are individually operated by saidmembrane portionsmoved by the fluid when the increasing pressure of the fluidsuccessively overcomes said different forces.

2. A membrane switch according to claim 1, said actuating meansincluding plates respectively secured to said membrane portions. 7

3. A membrane switch according to claim 1, said actuating meansconnecting one side of said membrane portions with said actuatingmembers, respectively, said fluid being applied to the other side ofsaid membrane portions.

4. A membrane switch comprising, in combination, a support; membranemeans mounted on said support and including a fold and a plurality ofindependently movable membrane portions separated by'said fold; aplurality of contact means mounted on said support, each contact meansincluding an actuating member movable between two positions; biasingmeans on said support for holding said members in one of said positions,said biasing means acting on said actuating members with differentforces; a plurality of actuating means connecting said membrane portionswith said actuating members, respectively, so that different forces aretransmitted to said membrane portions and movement of each membraneportion causes movement of the correlated actuating member to the otherposition thereof; and means for applying a fluid to said membraneportions so that said actuating members are individually operated bysaid membrane portions moved b the fluid when the increasing pressure ofthe fluid successively overcomes said different forces.

5. A membrane switch according to claim 3, said support comprising ahousing, said membrane means mounted on said housing and dividing saidhousing into two chambers, said contact means mounted on said housing inone of said chambers, and said means for applying a fluid to the otherside of said membrane portions connected to the other of said chambers.

6. A membrane switch comprising, in combination a housing; membranemeans mounted on said housing and including a fold means and a pluralityof independently movable membrane portions separated by said fold means,said membrane means dividing said housing into two chambers; a pluralityof contact means mounted on said housing in one of said chambers, eachcontact means including an actuating member movable between twopositions; biasing means on said housing for holding said members in oneof said positions, said biasing means acting on said actuating memberswith different forces; a plurality of actuating means connecting oneside of said membrane portions with said actuating members and includingplates respectively secured to said membrane portions so that differentforces are transmitted to said membrane portions and movement of eachmembrane portion causes movement of the correlated actuating member tothe other position thereof; and means connected to the other of saidchambers for applying a fluid to the other side of said membraneportions so that said actuating members are individually operated bysaid membrane portions moved by the fluid when the increasing pressureof the fluid successively overcomes said different forces.

7. A membrane switch comprising, in combination, a support; membranemeans mounted on said support and including straight fold means and twoindependently movable membrane portions separated by said fold means; aplurality of contact means mounted on said support, each contact meansincluding an actuating member movable between two positions; biasingmeans on said support for holding said members in one of said positions,said biasing means acting on said actuating members with differentforces; a plurality of actuating means connecting one side of saidmembrane portions with said actuating members, respectively, so thatdifferent forces are transmitted to said membrane portions and movementof each membrane portion causes movement of the correlated actuatingmember to the other position thereof, said actuating means includingsegment-shaped plates respectively secured to said membrane portions,said segment-shaped plates having straight edges located on oppositesides of, and adjacent said straight fold of said membrane means; andmeans for applying a fluid to the other side of said membrane portionsso that said actuating members are individually operated by saidmembrane portions moved by the fluid when the increasing pressure of thefluid successively overcomes said different forces.

8. A membrane switch comprising, in combination, a support; membranemeans mounted on said support and including a circular fold, an innermovable membrane portion surrounded by said fold, and an outer annularmembrane portion surrounding said fold so that said membrane portionsare movable independently of each other; a plurality of contact meansmounted on said support,

each contact means including an actuating member movable between twopositions; biasing means on said support for holding said members in oneof said positions, said biasing means acting on said actuating memberswith different forces; a plurality of actuating means connecting oneside of said membrane portions with said actuating members,respectively, so that different forces are transmitted to said membraneportions and movement of each membrane portion causes movement of thecorrelated actuating member to the other position thereof, one of saidactuating means including a circular member secured to said innermembrane portion, and another actuating means including an annularmember secured to said outer annular membrane portion; and means forapplying a fluid to the other side of said membrane portions so thatsaid actuating members are individually operated by said membraneportions moved by the fluid when the increasing pressure of the fluidsuccessively overcomes said different forces.

9. A membrane switch comprising, in combination, a housing; membranemeans mounted on said housing and including straight fold and twoindependently movable membrane portions separated by said fold, saidmembrane means dividing said housing into two chambers; a plurality ofcontact means mounted on said housing in one of said chambers, eachcontact means including an actuating member movable between twopositions; biasing means on said housing for holding said members in oneof said positions, said biasing means acting on said actuating memberswith different forces; a plurality of actuating means connecting oneside of said membrane portions with said actuating members,respectively, so that different forces are transmitted to said membraneportions and movement of each membrane portion causes movement of thecorrelated actuating member to the other position thereof, saidactuating means including segmentshaped plates respectively secured tosaid membrane portions, said segment-shaped plates having straight edgeslocated on opposite sides of, and adjacent said straight fold of saidmembrane means; and means connected to the other of said chambers forapplying a fluid to the other side of said membrane portions so thatsaid actuating members are individually operated by said membraneportions moved by the fluid when the increasing pressure of the fluidsuccessively overcomes said different forces.

iii. A membrane switch comprising, in combination, a housing; membranemeans mounted on said housing and including a circular fold, an innermovable membrane portion surrounded by said fold, and an outer annularmembrane portion surrounding said fold so that said membrane portionsare movable independently of each other, said membrane means dividingsaid housing into two chambers; a plurality of contact means mounted onsaid housing in one of said chambers, each contact means including anactuating member movable between two positions; biasing means on saidhousing for holding said members in one of said positions, said biasingmeans acting on said actuating members with diflerent forces; aplurality of actuating means connecting one side of said membraneportions with said actuating members, respectively, so that differentforces are transmitted to said membrane portions and movement of eachmembrane portion causes movement of the correlated actuating member tothe other position thereof, one of said actuating means including acircular member secured to said inner membrane portion, and anotheractuating means including an annular member secured to said outerannular membrane portion; and means connected to the other of saidchambers for applying a fiuid to the other side of said membraneportions so that said actuating members are individually operated bysaid membrane portions moved by the fluid when the increasing pressureof the fluid successively overcomes said different forces.

11. A membrane switch comprising, in combination, a M

housing; a membrane means mounted in said housing and including an innermembrane portion and an outer annular membrane portion surrounding saidinner membrane portion, said membrane means including an additionalportion intermediate said inner and outer membrane portions, saidadditional portion being constructed and arranged to permit movement ofsaid inner and outer membrane portions independently of each other, saidmembrane means forming in said housing at one side thereof a chamber fora fluid adapted to act on said membrane means; two contact means mountedon said housing on the other side of said membrane means, each contactmeans including an actuating member movable between two positions;biasing means on said support for holding said actuating members in oneof said positions, respectively, said biasing means acting on saidactuating members with different forces; a first actuating meansincluding a bellshaped member having an annular rim secured to saidannular membrane portion at said other side of said membrane means, anda projection connected with one of said actuating members, saidbell-shaped member having an opening spaced from said projection; asecond actuating means including a plate secured to said inner membraneportion and a projecting arm passing through said opening in saidbell-shaped member and connected with the other of said actuatingmembers so that said biasing means transmit diiferent forces throughsaid actuating means and members to said membrane portions and movementof each membrane portion causes movement of the correlated actuatingmember to the other position thereof; and inlet means on said housingcommunicating with'said chamber and adapted to supply fluid to the sameso that the fluid acts on said membrane portions whereby said contactmembers are individually operated by said membrane portion moved by thefluid when the increasing pressure of the fluid successively overcomessaid different forces. i

12. A membrane switch as set forth in claim 11 wherein said plate ofsaid second actuating means is substantially circular, and wherein saidprojecting arm projects from the periphery of said plate perpendiculariythereto; and wherein said projection projects perpendicularly from thetop portion of saidbell-shaped member of said first actuating means, andparallel to said projecting arm.

13. A membrane switch as set forth in claim 11 and including a guide pinprojecting from the center of said plate of said first actuating meanstransverse to said membrane means for movement with said inner membraneportion; and wherein said bell-shaped member of said first actuatingmeans has a central guide bore slidably surrounding said guide pin.

14. A membrane switch as set forth in claim 13 and including guide meanson said housing for guiding the free end of said guide pin.

15. A membrane switch as set forth in claim 11 wherein said plate ofsaid second actuating means has a projecting portion disposed to abutthe inner suface of the top of said bell-shaped member when said innermembrane portion is displaced by the pressure of the fluid wherebymovement of said inner membrane portion, of said projecting arm, and ofthe corresponding actuating member is limited.

16. A membrane switch as set forth in claim 15 wherein said plate iscircular, and wherein said projecting arm and said projecting portionproject from the periphery of said plate perpendicularly to the same andare located diametrically opposite each other; and including a guide pinprojecting from the center of said plate'perpendicularly to the same,said bell-shaped member having in the top thereof a guide bore for thepassage of said guide pin; and guide means on said housing for guidingthe free end of said guide pin. 17. A membrane switch as set forth inclaim 11 wherein said intermediate additional portion of said membranemeans is a circular fold convex toward the other side of said membranemeans.

18. A membrane switch comprising, in combination, a

support; membrane means mounted on said support and including a firstmovable membrane portion, a second movable membrane portion, :and meansintermediate said first and second movable membrane portions and including a portion of said membrane means and permitting said movablemembrane portions to move substantially independently of each other; aplurality of contact means mounted on said support; a plurality ofactuating means connecting said contact means with said movable membraneportions, respectively, so that movement of the latter causes actuationof said contact means, respectively; a plurality of biasing means forapplying different forces to one side or" said membrane portions; andmeans for applying fluid pressure to the other side of said membraneportions so that said contact means are individually actuated whendifferent fluid pressures act on and displace said membrane portions. 1

References titted by the Examiner,

UNITED STATES PATENTS 2,975,251 3/1961 Belleretal 20o-s1x 3,064,09411/1962 Marchi ZOO-83' 3,187,136 6/1965 C0rdcret.ai, 2QO81X BERNARD A.GILHEANY, Primary Examiner.

H. FLECK, Assistant Examiner.

18. A MEMBRANCE SWITCH COMPRISING, A SUPPORT; MEMBRANCE MEANS MOUNTED ONSAID SUPPORT AND INCLUDING A FIRST MOVABLE MEMBRANCE PORTION, A SECONDMOVABLE MEMBRANCE PORTION, AND MEANS INTERMEDIATE SAID FIRST AND SECONDMOVABLE MEMBRANE PORTIONS AND INCLUDING A PORTION OF SAID MEMBRANE MEANSAND PERMITTING SAID MOVABLE MEMBRANE PORTIONS TO MOVE SUBSTANTIALLYINDEPENDENTLY OF EACH OTHER; A PLURALITY OF CONTACT MEANS MOUNTED ONSAID SUPPORT; A PLURALITY OF ACTUATING MEANS CONNECTING SAID CONTACTMEANS WITH SAID MOVABLE MEM-